Birds (class Aves) are feathered, winged, bipedal, endothermic (warm-blooded), egg-laying, vertebrate animals.The fossil record indicates that birds evolved from theropod dinosaurs during the Jurassic period, around 160 million years (Ma) ago.Modern birds are characterised by feathers, a beak with no teeth, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton.Following are the list of birds found in Periyar Tiger Reserve.